PHOTIC REACTIONS OP HONEY-BEE 349 



Whether the effect of contact stimulation also accounts for 

 certain of the phenomena observed by Axenfeld ('99) is not so 

 clear. Axenfeld reports that nocturnal lepidoptera with one eye 

 blackened turned toward the blackened eye during the day. In 

 the same paper he makes the following general statement: "En- 

 fin on peut observer que ces m^mes animaux photofuges, qui tour- 

 nent en pleine lumilre du soleil du c6te de I'oeil convert, off rent 

 le mouvement contraire au soir ou meme de jour, quand ils sont 

 transport's dans une chambre mal 6clair6e; . . ."It 



may be that such animals, being attuned to a low intensity, re- 

 spond positively to it, whereas a stronger intensity evokes a nega- 

 tive reaction, somewhat according to the idea of Davenport ('97, 

 p. 197). Certainly, if the circling of the nocturnal lepidoptera 

 toward the covered eye was a hght response, it is not in harmony 

 with the statement of Loeb ('90, p. 51) to the effect that all 'day 

 a,nd night butterflies' are without exception positively photo- 

 tropic. I am led to suspect, however, that some of the reactions 

 noted by Axenfeld were the results of contact stimulus, for Hess 

 ('13 a, p. 651) has shown that Coccinella, which Axenfeld reports 

 .as circling toward the blackened eye, is not negative to light. 

 Axenfeld's experiments, therefore, need careful repetition before 

 any final conclusions may be drawn from them. 



It seems quite certain, therefore, that what have appeared to 

 be exceptions to the general occurrence of circus movements 

 among phototropic arthropods are not really incompatible with 

 this view. Taken as a whole, the investigations of these reac- 

 tions demonstrate rather conclusively that, although they may 

 be modified through experience or obscured by responses to other 

 than photic stimuli, they are, nevertheless, to be considered as 

 characteristic of phototropic arthropods. Photic orientation in 

 this group of animals, therefore, cannot be accounted for by any 

 theory which fails to offer a satisfactory explanation of circus 

 movements. 



